05-22-2016, 11:46 AM
You might be thinking of 25hz instead of 30hz. 25hz was used around the Niagara Falls area and the transformers are easily recognized because they are larger than their 60hz counterparts. Fortunately a 25hz transformer will run just fine on 60hz power, in fact it will run much cooler because it is larger (more iron).
John KK4ZLF
Lexington, KY
"illegitimis non carborundum"